Sulphur is an essential plant nutrient included in fertilizer compositions to improve crop performance. In order to be useable by plants, it is desirable that the sulphur be in the sulphate form.
Natural fertilizer products, or products that are certifiable as organic, are desirable. Elemental sulphur is one type of sulphur additive used in organic farming. Before elemental sulphur can be used by a plant, however, it must first be oxidized to sulphate form. The sulphates may then be taken up by the plants.
Alkaline (or basic) soils may slow sulphur oxidation, as may some other types of soil conditions (for example soil containing carbonates, which may be found in arid zones). In some cases, soil acidification may be needed to correct the soil pH where the pH is high. Soil acidification may aid in converting elemental sulphur to sulphate form. Microbial action may also aid in converting elemental sulphur to sulphate.